Hello and welcome to health care magic. Since the swelling appeared soon after the fall, we need to rule out the possibility of fracture of femur. Moreover the coumadin will delay clotting of blood and so there is a chance of Internal bleeding. Another area of concern is Urethral injury which can occur following a fall from ladder. So my advice is to take him to an Orthopaedic specialist and let the doctor have a look at his symptoms. He will take an xray and may be an ultrasound of pelvis. If they are normal, then there is nothing to worry. Hope this discussion will be helpful to you. Thank you.